Lightweight refractory metal structure



Feb. 23, 1965 B. KRAMER LIGHTWEIGHT REFRACTORY METAL STRUCTURE Filed July 5, 1962 FIG. I

INVENTOR BRUCE E. KRAMER BY 4% W ATTORNEY combustion products of the propellant reaction.

' of expansion.

LIGHTWEIGHT REFRACTORY METAL s STRUCTURE' Bruce E. Kramer, LovelamL-Ohio, assignor to the United States of America as represented by the Secretary of the Navy T Filed July 5, 1962,'Ser. No. 207,829 2 Claims. (Cl. 60.-.-35.6

I The present invention relates to high temperature structural'materials and methodsof fabricating articles therefrom. More particularly, the invention relates to rocket nozzles formed entirely from refractory metal materials. With the adyent'of solid propellant rocket engines, the extremely high-temperatures and gas yelocities generated resistant, high-strength, lightweight nozzle. 7

One of the prior art approaches to solve this problem have created a need fora temperature-resistant, erosionis to construct the nozzle out of standard metals 'such as steel or aluminum and to circulatevarious coolantsaround the external surface. However, this nozzle has not proven UnitedIS ates PatentOf ce 1 l f Patented Feb 23 1965 with suitable heat resistant material 8 such as ceramics.

and plastics.

FIG. 2, illustrates more clearlythe construction of the I nozzle wherein a plurality of fstrips 9 of tungsten .or tantalum are joined'by tantalum rivets 10 or arc sprayed tungsten. to the interior lands of. the corrugations 6 to form the inner shell 4.

The following describes the fabrication; process. Tungsten or. tantalum sheet is hot rolled -througha set of parallel gearswith tapered teeth to providea corrugated sheet which is then formed to the nozzle shape; the corrugations running in a'longitudinal direction. Thesheet.

is then joined by arc'sprayed tungsten or by tantalum rivets, for example. Strips of sheet tungsten ortantalum are then joined to the interior lands of the corrugations;

By longitudinally joining: together the interior lands of the corrugation the inside, liner of the nozzle is formed.

. The inside liner is then coated with arc sprayed tungsten,

' satisfactorysince it was too heavy, and demanded a'complex system to circulate the coolant. The usual approach was to fabricate the body of the rocket nozzle out of light weight insulative material such as graphite or ,plas

tic. Such insulativematerial wasthen coated on its inside surface with a high melting material such as tungsten to resist the temperatures and forces of the expelled A further object is to provide a nozzle that will resist the eroding forces of the high velocity gas stream.

A further object is to provide a method of constructinghafnium carbide or tantalum carbide which forms a coating of erosion resistant material and also joins together.

the strips of sheet metal. The sprayed coating may optionally bevacuum sintered. The outside corrugations may be filled with suitable ceramicv or plastic to stiffen and provide insulation. Theouter shell is attached to the corrugations and the inside diameter may then if desired ;be ground toa smoother surface. a

The apparatus by which the above steps may beper- .formed is not critical nor part of the present invention. The corrugator can be any one ofthose commonly available in the art such as one similar to the one disclosed by Pappelendam in U.S. Patent No. 2,746,139. The arc sprayed tungsten can be accomplished by electric arc furnaces commonly known or by a' plasma stream apparatus such as that disclosed by Giannini in US. Patent No. 2,922,869. As is Well known, tungsten melts at 6200 F. Though tantalum melts at 5400 F., 800 F; lower, it is more workable at room temperature and is thus easier to construct a nozzle out of this material; Of

the spray coated materials, tungsten has proven' most satisfactory and a 0.150, inch coating which was utilized in a solid propellant rocket engine did not come near 7 its melting point. The liner is formed of 0.060 tungsten a nozzle that is simple, reliable and relatively inexpensive. 1

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the followingdetailed description when considered in connection with the accompanying drawings in which like reference numerals designate like .partsthroughout the figures thereof and wherein: g

FIG. 1 shows a sectional view of a ment of the invention; and i FIG. 2 illustrates a section of the device taken on the preferred embodi line 2-2 of FIG. 1 looking in the direction of the arrows.

Referring now to the drawings there is shown in FIG. 1 a nozzle 3 constructed of an interior shell 4 composed of 'a series of longitudinal strips 4a of tungsten or tantalum.

Since the circumference of the nozzle 3 is considerably reduced at the throat section, the width of longitudinal strips 4a must be correspondingly reduced atthat point, as shown by Dalgleish in US. Patent N0. 2,976,679. Said shell is covered with acoating 5 of erosion resistant material such as tungsten, tantalum carbide and hafnium carbide. The shell is supported by, surrounded by, and

attached to a corrugated backup liner shown as corrugations 6 on FIG. 2. The corrugations can be joinedto an outer liner 7 of suitable material and the spaces between the corrugation and the outside liner can be filled or. tantalum sheet, but the corrugated sheet can be thinner. It should be understood that since the coeflicients of expansion and melting points of these 'two metals are so similar that the liner or-oorrugated backing may be made of either interchangeably, tantalum being preferred for 'uses below 5400 F. and tungsten being required for heats above 5400 F. 7

Thus, it is readily obvious that the nozzle is constructed completely out of refractory materials of ex tremely high melting point and erosion resistance. The mismatch of coeflicientof expansion is obviated since the materials have similar co'efiicients of expansion. 7 Even the joining materialsare refractory metals, i.e. tantalum rivets or are sprayed tungsten. The are sprayed tungsten can also be used to coat the innersurface of the liner and concomitantly thiscoating will weld the seams between the strips as it formsthe smooth inner surface. It should be understood that although the corrugations have been shown to run longitudinally,-it is also permissible to have the corrugations run horizontally and then join the longitudinal strips of refractory metal thereto. 7 p 'Obviously many modifications and variations of the I present invention are possible in light of the above teachings. 'It is, therefore, to be understood that within the scopeof the appended claims, the invention may be practiced otherwise than as specifically described.

What is claimed is: 1. A refractory metal rocket nozzle capable of withstanding temperatures and gas velocities generated during ignition comprising in combination a plurality of strips of refractory. metals arranged longitudinally to form an inner liner, coating means on said strips of refractory metal to provide erosion resistance and to form a continuous. inner surface, an outer liner; corrugated means supporting said inner liner in spaced relation With-said outer liner, insulating means between said inner and outer liners, and means-attaching said inner liner to said corrugated supporting means.

2. A rocket nozzle constructed substantially from re-' fractory metals such as tantalum and tungsten comprising in combination an inner liner composed of a plurality of longitudinal strips of one of said metals, a sprayed coat ing of a material selected from the group consisting of tungsten, hafnium carbide and tantalum carbide on said inner liner, corrugated refractory metal means supporting and insulating said inner liner and means attaching said inner liner to said corrugated support means.

10/40 11/43 4/51 10/52 11/53 l/SS 6/56 9/58 3/61 3/63 Aronson 29157 Egger et al. 29-157 Lubock 6039.69 .Fuller 6035.6 Nicholson 6035.6 Nicholson 60- 356 Rath 6039.69 Lowe 6035.6 Dalgleis-h 6035.6 Witt 6039.69

OTHER REFERENCES SAMUEL LEVINE, Primary Examiner.

ABRAM BLUM, Examiner. 

1. A REFRACTORY METAL ROCKET NOZZLE CAPABLE OF WITHSTANDING TEMPERATURES AND GAS VELOCITIES GENERATED DURING IGNITION COMPRISING IN COMBINATION A PLURALITY OF STRIPS OF REFRACTORY METALS ARRANGED LONGITUDINALLY TO FORM AN INNER LINER, COATING MEANS ON SAID STRIPS OF REFRACTORY METAL TO PROVIDE EROSION RESISTANCE AND TO FORM A CONTINUOUS INNER SURFACE, AN OUTER LINER, CORRUGATED MEANS SUPPORTING SAID INNER LINER IN SPACED RELATION WITH SAID OUTER LINER, INSULATING MEANS BETWEEN SAID INNER AND OUTER LINERS, AND MEANS ATTACHING SAID INNER LINER TO SAID CORRUGATED SUPPORTING MEANS. 